I have the Plusnet Business Broadband service using a Static IP address on the Plusnet Hub/Router.
I have a couple a SIP phones that register via a Session Border Controller using TLS/HTTPS/SRTP using ports 4431 and 5061.
If I reboot the router, the phones register. The next day the phones refuse to register until I reboot the router again. I've tried disabling the firewall and doing some port forwarding but still the same issue.
I'm wondering if there is still some PnP process happening that is blocking the incoming signals from the SBC. Using Wireshark I can see the web logon request from the handset hitting the SBC and passing through to the PBX and the SIP 200 OK returning from the PBX to the SBC, but it doesn't seem to be getting back to the handset without the reboot.
Any suggestions? I'll get a replacement router if that might solve the issue (unless Plusnet have a better option when there are problems). It's the standard Sagemcom Hub One I have.